A Gainesville teen has been arrested for allegedly assaulting a person during a meet-up for an online sale in December. Gainesville Police Department officials said Jeremiyah Eurell Leonard, age 18, was arrested Monday on more than 20 total charges including multiple counts each of aggravated assault, armed robbery and theft by taking for the December 29 incident. Officials said Leonard is also believed to be the suspect in a separate robbery in January…